/* =========================================
   MatAI-DU Landing Page — Ambient Professional
   ========================================= */

@import url('https://fonts.googleapis.com/css2?family=Inter:wght@400;500;600;700&display=swap');

:root {
  /* Ambient Blue-Green Palette */
  --bg-page: #F3F6F8;
  --bg-surface: #FAFBFC;
  --bg-card: #FFFFFF;
  --bg-gradient: radial-gradient(100% 120% at 50% 0%, #F8FAFB 0%, #EEF2F4 100%);

  --text-primary: #1A2A30;
  --text-secondary: #4A5D66;
  --text-muted: #7A8D96;

  --accent: #4A9092;
  /* Muted Teal */
  --accent-hover: #367072;
  --accent-light: #E9F3F3;
  /* Soft Seafoam */
  --accent-border: rgba(74, 144, 146, 0.18);

  --border: #D6E0E4;
  --border-soft: #E9EEF1;

  /* Shadows & Depth */
  --shadow-sm: 0 1px 3px rgba(26, 42, 48, 0.04), 0 1px 2px rgba(26, 42, 48, 0.02);
  --shadow-md: 0 6px 18px rgba(26, 42, 48, 0.06), 0 3px 8px rgba(26, 42, 48, 0.03);
  --shadow-hover: 0 10px 26px rgba(26, 42, 48, 0.08), 0 4px 12px rgba(26, 42, 48, 0.04);

  /* Layout & Typography */
  --font-sans: 'Inter', system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  --radius-md: 5px;
  /* Reduced roundedness */
  --radius-lg: 7px;
  /* Reduced roundedness */
  --space-xs: 0.5rem;
  --space-sm: 0.75rem;
  --space-md: 1.25rem;
  --space-lg: 2rem;
  --space-xl: 3rem;

  --transition: 0.25s cubic-bezier(0.4, 0, 0.2, 1);
}

*,
*::before,
*::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-sans);
  color: var(--text-secondary);
  background: var(--bg-page);
  background-image: var(--bg-gradient);
  line-height: 1.65;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* =========================================
   HEADER
   ========================================= */
header {
  background: linear-gradient(180deg, var(--bg-surface) 0%, #F2F5F7 100%);
  border-bottom: 1px solid var(--border);
  padding: var(--space-xl) var(--space-md);
  text-align: center;
  max-width: 1100px;
  margin: 0 auto;
  width: 100%;
  position: relative;
}

/* Ambient top accent line */
header::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 2px;
  background: linear-gradient(90deg, transparent 0%, var(--accent) 40%, var(--accent) 60%, transparent 100%);
  opacity: 0.65;
}

.header-title {
  font-size: clamp(1.8rem, 4vw, 2.5rem);
  font-weight: 700;
  color: var(--text-primary);
  letter-spacing: -0.015em;
  line-height: 1.2;
  margin-bottom: var(--space-sm);
}

.header-desc {
  font-size: 1.05rem;
  color: var(--text-secondary);
  max-width: 660px;
  margin: 0 auto var(--space-md);
  line-height: 1.6;
}

.header-hint {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  font-size: 0.8rem;
  font-weight: 500;
  color: var(--accent);
  background: var(--accent-light);
  border: 1px solid var(--accent-border);
  padding: 0.35rem 0.9rem;
  border-radius: 20px;
  letter-spacing: 0.01em;
  transition: var(--transition);
}

.header-hint::before {
  content: "●";
  font-size: 0.5rem;
  color: var(--accent);
}

.header-hint:hover {
  background: var(--bg-surface);
  border-color: var(--accent);
  transform: translateY(-1px);
}

/* =========================================
   MAIN & PROJECT CARD
   ========================================= */
main {
  flex: 1;
  padding: var(--space-xl) var(--space-md);
  max-width: 1100px;
  margin: 0 auto;
  width: 100%;
  display: flex;
  justify-content: center;
  align-items: flex-start;
}

.project-row {
  width: 100%;
  max-width: 840px;
}

.project-card {
  display: block;
  background: linear-gradient(175deg, var(--bg-card) 0%, #F8FAFB 100%);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: var(--space-lg);
  text-decoration: none;
  color: inherit;
  box-shadow: var(--shadow-sm);
  position: relative;
  overflow: hidden;
  transition: var(--transition);
}

/* Left accent indicator */
.project-card::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  width: 3px;
  height: 100%;
  background: var(--accent);
  transform: scaleY(0);
  transform-origin: top;
  transition: transform 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

.project-card:hover,
.project-card:focus-visible {
  border-color: var(--accent-hover);
  box-shadow: var(--shadow-hover);
  transform: translateY(-3px);
}

.project-card:hover::before,
.project-card:focus-visible::before {
  transform: scaleY(1);
}

/* Arrow cue on hover */
.project-card::after {
  content: "↗";
  position: absolute;
  bottom: var(--space-lg);
  right: var(--space-lg);
  font-size: 1.15rem;
  color: var(--accent);
  opacity: 0;
  transform: translateX(-6px);
  transition: var(--transition);
}

.project-card:hover::after,
.project-card:focus-visible::after {
  opacity: 0.75;
  transform: translateX(0);
}

.card-top {
  margin-bottom: var(--space-md);
}

.project-title {
  font-size: 1.32rem;
  font-weight: 600;
  color: var(--text-primary);
  line-height: 1.35;
  letter-spacing: -0.01em;
}

.card-meta {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-xs);
  margin-bottom: var(--space-md);
}

/* TAGS: Fixed hover behavior (no link mimicry) */
.tag {
  font-size: 0.74rem;
  font-weight: 500;
  background: var(--accent-light);
  color: var(--text-secondary);
  border: 1px solid var(--border);
  padding: 0.22rem 0.6rem;
  border-radius: var(--radius-md);
  letter-spacing: 0.01em;
  transition: var(--transition);
  cursor: default;
  /* Explicitly non-interactive */
  user-select: none;
}

.tag:hover {
  background: var(--bg-page);
  border-color: var(--border-soft);
  color: var(--text-primary);
  /* Removed transform & dramatic color shifts */
}

.card-desc {
  font-size: 0.96rem;
  color: var(--text-secondary);
  line-height: 1.65;
  margin: 0;
}

/* =========================================
   FOOTER
   ========================================= */
footer {
  background: linear-gradient(180deg, #F4F7F9 0%, #EDF1F4 100%);
  border-top: 1px solid var(--border);
  padding: var(--space-lg) var(--space-md);
  text-align: center;
  margin-top: auto;
}

footer p {
  font-size: 0.84rem;
  color: var(--text-muted);
  margin: 0.25rem 0;
  letter-spacing: 0.01em;
}

footer p:first-child {
  font-weight: 500;
  color: var(--text-secondary);
  margin-bottom: 0.4rem;
}

footer a {
  color: var(--accent);
  text-decoration: none;
  border-bottom: 1px dashed var(--accent-border);
  transition: var(--transition);
}

footer a:hover {
  color: var(--accent-hover);
  border-bottom-color: var(--accent-hover);
}

/* =========================================
   RESPONSIVE & ACCESSIBILITY
   ========================================= */
@media (max-width: 720px) {

  header,
  main,
  footer {
    padding: var(--space-lg) var(--space-sm);
  }

  .project-card {
    padding: var(--space-md);
  }

  .project-title {
    font-size: 1.18rem;
  }

  .header-desc {
    font-size: 0.98rem;
  }

  .header-hint {
    font-size: 0.75rem;
  }

  .project-card::after {
    display: none;
  }
}

@media (prefers-reduced-motion: reduce) {

  *,
  *::before,
  *::after {
    transition-duration: 0.01ms !important;
    transform: none !important;
  }
}

:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 3px;
  border-radius: var(--radius-md);
}